土壤中铬对油菜生物有效性的研究

Research on Bioavailability of Chromium in Soil to Cole Plant

通过在铬严重超标的污染土壤中盆栽油菜试验,研究种植油菜前后土壤中铬的各种赋存形态的变化,考察了油菜生长对铬赋存形态的影响,探讨典型重金属铬的生物有效性与其总量及各种存在形态之间的关系。结果表明,土壤中铬以铁锰氧化物结合态、碳酸盐结合态和残渣态为主要的存在形态,在油菜生长过程或其他环境因素的影响下,铬交换态、碳酸盐结合态、铁锰氧化物结合态和有机结合态均有可能被释放出来成为有效态,存在被油菜吸收的可能性,这些形态在土壤中的浓度构成了活动性污染物的总浓度,而残渣态不能被释放出来,不能成为活动态。提出了采用活动性污染物的总浓度(TCAS)作为重金属在环境中行为和作用的评价指标。

By the pot experiments on the cole planting in chromium seriously contaminated soil, the changes of the various forms of chromium in the soil pre- and post-planting cole is investigated, and the the effect of the cole growth on different forms of chromium is studied, and the relations of the bioavailability to the total content and various forms of the typical heavy metals are discussed. The results indicate that the chromium in the tested soil mainly in the forms of Fe-Mn oxide bound fraction, organic-bound fraction and residual fraction. On the effect of the cole growth or other environmental factors, the forms of exchangeable fraction, cai-bonate bound fraction, Fe-Mn oxide bound fraction, organic-bound fraction are all probably released and become active specie, so they may be absorbed by the cole. The total concentration of active specie （TCAS） in soil is composed by these forms. However, the residual fraction can not be released or become active specie. The total concentration of active specie （TCAS） is proposed as the appraise index of the activity and effect of heavy metals in soil.